Automatic telephone system



Dec 18, 1928. 1,695,267

F. ALDENDORFF AUTOMATIC TELEPHONE SYSTEM Filed Jan. 12, 1925 4Sheets-Sheet 1 Dec. 18, 1928. 1,695,267

F. ALDENDORFF AUTOIA'IIC TELEPHONE sYs'ral Filed Jan 1925 4 Sheets-Sheet2 Dec. 18, 1928.

F. ALDENDORFF AUTOMATIC TELEPHONE SYSTEM 4 Sheets-Sheet Filed Jan. 12,1925 mm vk Dec. 18, 1928.

1,695,267 F. ALDENDORFF AUTOMATIC TELEPHONE SYSTEM Filed Jan. 12. 1925 4Sheets-Sheet 4 49 g 44/ I i 42* 4 a 0 0 Patented Dec. 18, 1923.

UNITED STA E PATENT oFFi-cs.

ram: Ammmom, a mBnm-mfinnsnonn GERMANY; cashmere ALDBNDOBFF music! mumsnmnmonrr, DECEASED.

m TELEPHONE srs'rau.

Application filed-January 12 192 Scria1'No.1,889, and in Germany January14, 1924.

This invention relatesto selectoi'js andtelephone systems operating withselectors and its object is to provide devices by wh ch wrongconnections rising from the fact that 5 the line finders, grou selectorsetc. operate too slowly to res n to very uick movenients of the switccontrollers, are obviated.

In accordance with the invention a selector is used inwhich there isprovided for every line connected to its contact bank a designattact,and a brush that wipesover the designating contacts and throughawhichacurrent flows that passes through an electromagnet which causes thevoice current breshes to be stopped on a certain line. The hrushes arestop by a detent thatengages with teethof the sh carrier. In accordance,with another feature oftheinvention the brushes are stopped by anarmature (retracting) of an electromagnet and a member moved with thebrushes thathas as many teeth or the like as there are individualsets ofcontacts in the contact bank. The res nseof the electroet armature isaoce erated-in accordance wit the invention by ooaincctinga'condenserin. parallel to the electromagnet or weakening the exciting current ofthe electromagnet after its armature has been attracted,or by causingthe armature to retract through the efl'ectof counteracting ampere,turns.

A further feature of the invention consists in a selector in whichoneand the same magnet is used for starting and stop ing the selectorbrushes. Themagnet maybe arranged to start the selector when it isenergized and to stop its operation when the magnet is de-energized. 4vention consists of driving the brushes of a selector by a power such asspring wer, and in case they are not stopped on t e desired line, inmoving them step- I K-step by an electromagnet armature until t ey reachthedesired line. The step-by-step motion may be obtained by arrangingthe electromagnet armature so that it engages with the teeth of thebrush carrier and liberates one tooth after another. In accordancewithafurther feature of theinvention the line a on whose contacts in thecontact bankpf t a selector the brushes have been stopped, is marked bychanging the potential of a plurality of bank contacts Further features015: the invention consist in using a selector vofcthef aforedescribedkind asa line findexggroap selector mg contact in addition to theusualtest con- A further featureof the inorconnector. The brush carriermaybe ar ranged to execute rotary motions only or it may be arranged toalso'be moved longitudinal y. i

The invention is illustrated in the drawing in which 7 y 1 v =Fi'g. 1shows a constructional form of the selector and Fig. 1 showsa part of aselector whose brush carrier may be moved longitudinally and rotated.

Fig. 1 shows the longitudinal movement cF'cmtrolling mechanism a of theswitch of ig. 2 shows acircuit arrangement for the selector when used asa linefinder.

I Fi 3 shows circuits of a selector with a longitudinally movable "androtary brush shaft. I a

, Fig. 3 illustratescircui'ts of a group selectorwhose brushes executerotary movements only.

Fig. 4 shows circuits of a connectorfthat executes rotary movementsonly. i

,F'g. 5 shows a circuit in which the quick stopping effect-of thestopping magnet is obtainedby inserting a resistance in its energizing.circuit. q i

.Fig. 6 shows a cir'cuitin which the quickstoppingeffect of thestoppingmagnct armature is attained by counteracting ampere turns.

a F ig. 7 illustrates a form of the selector in which,,instead of twotoothed wheels as in Fi 1 only one toothed wheel is employed.

7 ig. 8 illustrates diagrammatically a portion of the. contact bank andshows the displacement of the designating contacts Selectors whosecircuits are arranged as shown in Figs. 2, 3 and 4 may, on the whole, bebuilt in the manner illustrated in Fig. 1 except that a cam disk 300,Fig. 3 or 400,

'Fig. 4 which is not provided in Fig. 1, is

combined with the brush carrier when the selectoris to be usedas a groupselector or connector; 7 p y i I 1 a In Fig. 1', 1 is a shaft which hasbrushes 2,

3, 4', 5 fiixed to it that are insulated from each other and from theshaft. Also fixed on the shaft 1 is atoothed wheel 6 whose hub 7 restson the bearingS. J ournalled so as to rotate on the shaftl toothed wheel10 with a spring box 9. The spring box 9 has an upwardlyextending hub 11and a downwardly extending hub 12 that rests on abushing 13 fixed to theshaft 1. I One end of the spring 14 sprint? iox 9 rotated in thedirection of the arrow 16, a holding pawl not shown) being providedwhich prevents backward rotation of the spring box 9. hen the spring box9 is wound up the wheel 17 is held against movement by the pawl 18 ot amagnet 19 so that the shat-"t 1 with the brushes i3. 3, 1. is alsoprevent mil from rotating. Mounted on the wheel 1'? are two slip rings29 to which current is conduct. by two brursihcs 21. Thetwo slip ringsare intercounected by a contact that is carried round with the wheel 11'when this wheel is moved out of its normal rotary position with respectto the spring box 9. int as soon as the wheel occupies a certainposition with respect to the wheel 1? a pin 21- ot the wheel 10 raises apin 23 and thus opens the contact that interconnects the rings 20. Thiscontact or switch designated 25 in The spring 11, when it is wound up,tends to turn the brush carrier 1 with its wheel 17 in the direction ofthe arrow 26 and it executes a turn in this direction when the startingand stopping magnet 19 is energized.

In a selector with a longitudinally movable shaft 1. Fig. 1, a toothedwheel 1'? corresponding to the wheel 17, Fig. 1 and a spring be); 9corresponding to the spring box 9, Fig. 1. and having a circle of teeth19, is provided. The toothed wneel 17 however has a hollow hub 7 uponwhich the springbox 9 is adapted to rotate. The shaft 1 extendsdownwardly through the spring box and has a series of circular teethwith which the pawl of a lifting magnet 28 may engage. The shaft 1" hasa groove 29 into which a pin 30 arranged in the box 01 the wheel 1'?protrudes. so that the shaft 1 may move lengthwise in the wheel 17 butcannot turn therein. l'lj' the litting magnet 28 the shaft 1. may belifted step-by-step and when the wheel 17 is then released by a magnetcm'respoinfliug to n'iagnet 19. 1, the shaft is rotated by the spring1-1 of the spring box until it is stopped in the manner hereinafterdescribed. The shaft 1 is restored to its normal position by its beingturned until a pin 31 of the same strikes against a slide way in theform of a long stop 3;. When the snatt is in this position a holdingpawl 33, Fig. 1 will register with a groove 34.- in the shaft so thatthe latter drops down. \Vhen the pin 31 has fallen beneath the slide way-32 the spring turns the shaft a little further round until the pin 31is restored to the position shown in Fig, 1 and the holding pawl 201,Fig. 8. engages with the wheel 17 and holds it and the brush carrier inthe normal position indicated in Fig. 3.

ply placing Figs. 2, and 4 side by side a complete circuit arrangementfor an exchange with line finders, Fig. 2, group sclectors, Fig. 3 andconnectors. Fig. i, is obtained.

It will now be assumed that a subscriber S, Fig. 2, desires to establisha connection with the line 224. When the subscriber S raises hisreceiver a current flows "lfrom the positive pole through the line relay-19, con tact 41, sub-station S, contact lil of the cut oti' relay 43 tothe negative pole. T he line relay 40 closes its contact 41. and openscontacts to, -17. The opening of the contacts 16, 17 results in thepositive pole being disconnected from the designating contacts 48, 49.By the closure of the contact -15 the cut-otl' relay 43 is connected tothe test wire 59 and test contact- 51 of the cilling subscriber. Atcontact 11 a circuit closed which extends from the positive pole throughthe starting relay 51 ot' the line tinder 52. T he relay 51 sends acurrent from the positive pole through its contact 53, brush 5%. of thetrunk finder, contact of relay 56, starting magnet 19 to the negativepole. The starting magnet 19 pulls its stopping pawl 57 away from thewheel 17 and this latter is now turned at a high speed by the spring 11,Fig. l. lVhen the wheel 1? with the brushes 58. 59, 60, 61 is moved outof its normal position the off-normal switch is closed and the relay 56is energized. The starting magnet 19 is then maintained encrgiz d by acurrent that flows through the contact 62 of the relay 64, wiper and thedesignating bank contacts 65 that are connected to the positive pole oi"the battery. The magnet- 19 remains energized until the. brush 58reaches the bank contact =19. The armature 57 then retracts and stopsthe wheel 17 so that the wipers 59, 60, in are held on the contacts 66,67. 69. If magnet 19 does not operate .tast enough it could happen thatthe brush 5S over-steps the contact 4 9 and only stops on the next;contact 48 from which the positive pole is also disconnected by thecontact 4-7. In any case. if necessary, as many contacts 48, 49 aredisconnected from the positive pole as are necessarv to prevent thebrush 58 from flying past the last b nl; contact that is disconnectedfrom the positive pole. which n'iight happen it' the armature 57 actstoo slowly. The calling line is always the one that corrcspoinls to thelast contact 48 that is disconn cted from the P it ve pole. \Vhen thebrushes are stopped n the first cmitact 419 disconnect d from thepositive pole the magnet 19. as soon as its armature L39 falls back,receives a current inipulse that flows through contact 69. T9. 71. (33to the negative pole. The armature 57 is thus again attracted and allowsthe toothed wheel 17 to turn through an angle corresponding to a furthertooth in the direction of the arrow, because. in consequence of theinterruption at 69 and of the disconnection lit) of the positive polefrom the contact 48, the armature 57 immediately drops back again andagain stops the wheel 17; The .test

brush 58 will now be resting on the bank con tact 51 which is connectedthrough the cutoil' relay 43 to the negative pole. Hence the relay 72will be energized by acurrent flowing from the positive pole through 53,5-4, 72, 59, 51, 45, 43 to the negative pole. 'Tho self-interrupter69"is switched off at 70 so that the armature 57 of the magnet 59 mainsstill. It is to be noted that the magnet 19 is made to allow itsarmature 57 to drop back extremely quickly by a'condcnser 7 3. The relay72 closes its contact 7 3 vand thus renders the calling line engaged sothat further relays like 72 or test relays in the connee-tors :unnot beenergized when the brushes of other selectors are stopped on the bankcontacts of the calling line. The relay 72 by its contacts 74, 75 alsoconnects the calling line through to the group selector, Fig. 3, so

that the impulse relay 202 of the group solector is energized.Furthermore the relay 72 by its contact 76 opens the circuit of therewinding magnet 15 which would otherwise be closed when the releaserelay 203and the relay 64 are energized. The calling sub scriber nowsends in a series of two impulses, i. e. he causes two interruptions ofhis loop to ,take place in rapid succession so, that the armatures 204,205 drop back twice and two impulses flow fromthe negative pole throughcontact 206 which" was closed (due to a current from the negative poleto 204, 203', 207 to the positive pole) when the relay 202 was firstenergized, contact 208, c0ntact209, lifting magnet 28 to the positivepole. The lifting magnet 28 now raises the shaft 1, Fig. 1 with thebrushes 210, 211, 212, 213 step-by-step until they reach the secondlevel of the contact bank. The calling subscriber having now sent inhistwo hundred-impulses, the armatures 204, 205 now remain attracted fora relatively long interval so that the relay 214 which was energizedthrough 206, 214, 215 is kept short circuited at contact 216 until itsarmature drops back and the contact 217 is closed. As the verticaloif-normal switch 218 was closed at the first vertical step of the shaftthe starting magnet 219 now receives a current which flows from theregative pole through 220, 218, 217, ofi-normal switch 221,229 to thepositive pole. The wheel 17' and the shaft 1 with the brushes 210213 isnow released for rotary movement so that the spring 14' whirls thebrushes round until the magnet 219 which is bridged by a condenser 222and receives current during rotation of the brushes through the contact223, brush 213 and bank contacts such as 224 connected to the negativepole, is de-energized. This de-energiaa tion takes place as soon-as thebrush 213 reaches :1 contact 224 Whose wire 225 is due 212, wire 228,resistance 401, oil-normal sends in twotens impuls s.

t, 'msl contact 41f left hand windin connected from the negative polegthis wire leading to a tree connector, Fig. 4. The stopping pawl 207engages with the wheel 17 and arrests the brushes 211, 212, 213 on wiresleading to the connector, Fig. 4. In the group selctor, Fig. 3 therelay'226 is now energized by a current thatflows from the negative polethrough 220, retracted armature 227 of the magnet 219, 220, brushcontact 402 of the connector to the positive pole. The relay 226 opensthe contacts 229, 230, 231 and at the some time extends the voicecurrent wires through the wipers 210, 211 to the impulse relay 402 ofthe connector. The impulse relay 202 of the group selector isdisconnected at contacts 230, 231. This does not however result in therestoration of the group selector because the short circuitaround therclcaserelay 203 is kept open at contact 22:. The calling subscriber nowOn the first retraction of the armature otthe impulse relay 402 acurrent impulse flows from the negative pole through contact 400, 407,408, wire 409, bank contact 410, wiper 414, contact 415 and through themagnet 419 bridged by the condenser 420. The magnet 419 pulls wheel 417so that this wheel with the brushes 411 414 is rotated. brush 414 leavesthe contact 410 but is immediately re-coiinected to negative potentialby a long contact 421 so that the magnet 419 remains energized until thebrush 410 reaches the contact 422, which in the meantime will have l vendisconnected from the negative pole by the rc-energization of theimpulse relay 402. The magnet 419 thus allows thesto 'iping pawl418 tore-engasre with the wheel 4 .750 as to stop thc'brushcs 411, 41.4 on theset of bank: contacts corrcsp mding to the 411--414 is wound in such away that the long steps of the brushes keep pace with the numericalimpulses from the suliiscribcr. During the inter after the series oi tenimpulses have been sent in the clni-nge over relay 424., which wasenergized by a current from the negative pole throu wl'i 0o, 4.25 to thepo. t' pole is do -en: the short circuit closed at 420 so relay 427 ise'ner ized by a 0m from the negative pole throi.

n 5 ii) the positive pole. The impulse wire 431. is connected hytlierelay 427 and through contact 421 to an in .c-rrupter controls 1 by acam disk 409/- :md'tlnoim h th s i 'ieilupter and a contact 434 itextends to the toothedmutant isfully re-woundthe circuit of the rewind--ing magnet 15 is o ened at contact 83. In cases in which. a subscriber Sreplaces his receiver,pwithout ebrushes 58, 59, 60,

61 havingreac-hed his, bank contact set, the relaytiel is energized by acurrent that flows from the positive. pole through 85, 86, 87, leftwinding of 64 to thenegative pole. The re;

pulses which flow from the negative pole through theinterrupter 89,contact 90, magnet 88, brush 87, contact 83 to the positive pole. Thebrushes of the trunk finder are thus stepped forward until they reach atrunk whose associated contact83 is open.

In Fig. 7 a. manner of arrangingthe circuits in connection with thedesignating contacts of the line -finder is shown in which the inewla 3.f ra amp ea of a l scriber so, isconnects the battegyfrom twodesignating contacts 91, 92 asin Wig. 2. The arrangement of Fig. 7differs-from that of Fig. 2 however in thatthe callin line is connectedto the bank contact set 0 the desi nating contact 92 that is firstreached by he finder wipers and thebrushes, if they should overstep thedesignating contact 92 and only be sto ped at. thenext contact 91, arestepped bad by a magnet 93 onto the contact 92.

In the arrangement shownin v5 the stopping magnet 19 is notbridged acondenser, but its quick operation is rought about by a resistance 94beingincluded in its energizing circuit as soon as it has attracted itsstopping pawl57'. I

In Fig. 6 the stopping magnet 19' has two coils. Theretractlon of thestopping pawl is brought about by the ampere turns of the energizin by'awin mg 96 at the moment in .which the brush 97 reaches adesig'natedcontact. The counteracting ampere turns 96 are stronger to a certaindegree than thearnpere turns 95 but not so strongasto cause theretracted stoppingpawl to be attracted again.

In Fig. 3? a group selector is shown which executes long rotary steps inresponse to numerical impulses instead of vertical steps. This isaccomplished by means of a camldisk 300. The operation of'the selectorwill be obvious from the following description ofthe operations thattake place in setting it onto the desired bank contact oup.

When a calling party as been connected through to the group selector,Fig. 3, its imwinding 95 being counteracted pulserelay 3.01 isenergized. Italso results in the energization of the release relay 302(negative pole, 303, 302, resistance 304, positive pole). Assumingthatthe callingsubscriber sends in two numerical impulsesso that thearmature of the relay 301 drops back twice, a current impulse will flowat each retraction" of the'armature from the negative pole through 305,306, 307, 308, ar- I resting magnet 319, to the positive pole. The

magnet 319 pulls-the holding pawl 320 away from the toothed WllGCl 321and this Wheel with the cam disk300 and the brushes 322. 323,324, 325 isrotated b the tensioned spring (similar to 14, Fig. 1 As soon as thepawl320 is disengaged from the tooth of the wheel 321and this wheelturns through a fraction ofthe pitch of the teeth the cam disk 300closes thecontact 326, 327 so that the magnet 319 receives a currentthat flows from the negative pole through 327,326, 307, 308, 319 to thenegative pole. The magnet 319 now remains energized until the spring 326drops into the next notch 329 of the disk 300 so as to open the contact327 and cause the pawl 320 to engage with a tooth of the wheel 321. Thebrushes 322-325 will now have executed one tens step. The next numericaliinpulse will now re-energize the magnet 319 in a circuit extendingironi the negative pole through 305,306, 307, 308, 319 to the positivepole. [The stop ping pawl. 310 is Q igainwitlidrawn from the toothedwheel 321, t

e contacts 326, 327 are again closed until thespring 326 drops into thenotch .329 and the holding pawl. 320 againcngages the wheel 321; andithebrushes will then have completed.

their second. long step.

In the interval that ensucsafter the series of numerical impulses thechangeover relay 330 is d e-energiz'ed by its being short-circuited atcontact'331 so that the contact 332 is closed an'dthe relay 333 isenergized by a current flowing from the positive pOle throughf332, 333,ofi-norinal contact 334 to negative pole. The relay 333 by its contact334 now co'nnects the magnet 319 to thebrush 325. If the brush 325 isnow standingon the bank contact of a freetrunk the magnet 319 remainsde-energized and a current flows through the relay 336 in a circuit thatextends from the positive polethrough 337, 336, 325, .wire338 to thenext selector ahead. The relay 336 thus extends the calling party to thenext selector. But if the brush 325 is standing on a busy trunk, thatis'a trunk whose test wire is connected by a con tact 339 in theconnector to the negative pole, the magnet 319 will be energized by .acurrent flowing from thepositivc pole through 319,308, 307, brush 325,contact 339 to the negative pole. The magnet 319 then again withdrawsthe holding pawl 320 from the wheel 321 and the brushes are rotated bythe tension spring until brush 325 reaches a test or designating contactthat is not connected with the negative pole and therefore belongs to atree trunk. The holding pawl 320 now drops into the wheel 321 andarrests the brushes on the contact set of the tree trunk. lVhen thecalling subscriber replaces his receiver he contacts 405, 408 are openedand contacts ii l0, 341 closed. The magnet 319 s now energized by acurrent flowing through the cit-normal contact 334, 341, 319 to thepositive pole and this current continues flowing until the cam disk 300presses the cam 34-2 against the spring 3% and thus opens the oft-normalcontact 334. The holding pawl 320 is then released by the magnet 319 andthe toothed wheel 321 with the cam disk 300 and the brushes is thenarrested by the holding pawl 320 in the normal position illustrated. Therewinding magnet 34:5 receives impulses that flow from the negative polethrough the interrupter 346, contact 340, 3&5, contact 3&7 until thecontact 347 is opened by a cam 34S mounted on the spring box. The springnow being fully re-wound the rewinding magnet 345 is de-energized.

In Fig. 8 the positions of the bank contacts with respect to each otherare diagran'nnatically illustrated. From this illustration it appearsthat the designating contacts (as F 48. 49) are displaced with respectto the other contacts of the contact row so that the voice currentcontacts 51, 51 and the contacts 51 connected to the holding wire areopposite to gaps betwen the contacts 41-8, 49. The holding pawl of thestopping magnet is adjusted so that it arrests the toothed wheel (e. g.17, Fig. 2) moved with the brushes in a position in which the contactingends of the wipers stand on a gap between two designating contacts butin the middle of the associated bank contacts 51, 51, 51 By thisadjustment the greatest time of de-energization of the stopping magnetis attained.

Instead of displacing the bank contacts the same result can of course beobtained by displacing the ends of the brushes with respect to eachother in a corresponding manner.

In reference to the selector shown in Fig. 1 it is to be mentioned thatinstead of the groove 29 and the pin 30 a guide fork 40 placed near theperiphery of the wheel 17' and a guide arm 41 projecting from the shaft1 and arranged to slide in the fork 40 may be provided. By thisarrangement the play between the shaft 1 and the Wheel 17 can easily bereduced to a fraction of 21 millimetre.

It is also to be noted that the contact 433 may simply be opened andclosed by the stopping pawl 418 instead of using a special cam disk L00for this purpose. The cam disk e00 could then be dispensed with.

I claim 1. In a selector switch, a brush, bank contacts, aself-contained power device for driving said brush to any desired bankcontact and then to a normal position, a b1usliarresting member thatmoves with said brush, an clectromagnet whose armature stops the brushon its deenergizing, and a circuit through said bank contacts for theelectronn jnet which is opened when the brush reaches a desired bankcontact.

An electrically operated switch com prising bank contacts, a brush, aself-contained power device that rotates the brush always in the samedirection, a toothed brusharrcsting member that travels with the brush,an electroniaguetically operated stopping member adapted to engage withthe teeth of said arresting member to stop the brush on any individualbank contact, electric circuits local to the switch which include bankcontacts of same for controlling said stopping member, and a line loopfor controlling said local circuits.

3. An elcctricall y operated switch comprisng bani: coi'itacts, a brush,a spring that rothe brush always in the same direction, .oothcdbrush-arresting member that travcls with the brush, anelectromagnetically operated stopping member adapted to engage with theteeth of said arresting member to stop the brush on any individual bankcontact. electric circuits local to the switch for controlling saidstopping member, and a line loop for controlling said local circuits.

+L. In a selector switch, a brush, bank contacts, a spring for drivingsaid brush to any desired bank contact and then to a normal position, aln-ush-arresting member that moves with said brush, and an electromagnetwhose. armature stops the brush on its deenergization.

In a switch, bank contacts, a toothed wheel, brushes that wipe over saidcontacts. a self-contained power device for moving the bresaes andtoothed wheel always in the same direction, a stopping pawl normally inengugem-cnt with said toothed wheel, an electromagnet for lifting saidpawl from the toothed wheel to start the motion of the brushes and forletting the pawl engage with the wheel to stop the brushes on anydesired individual set oi": bank contacts, and a condenser whichinfluences said electromagnet to quicken the action of its armature.

G. In combination with a link circuit or trunk, bank contacts, brushesthat wipe over the bank contacts, a brush carrier, a toothed member onthe brush carrier, a brush-stopping member, an electromagnet foroperating the brush-storming member, a power device for driving saidbrush carrier in a continuous motion until the brushes reach a desiredset of bank contacts, a starting circuit for starting the motion of thebrushes. a inotion-inaintaining circuit including said electromagnet.one of said brushes and bank contacts over which it travels, a trunkconnecting relay for lid til

messes I means for propelling the brushes, a test mag net for testingthe condition of the bank contacts and stopping the action of thepropelling means when the brushes reach hank contacts that are in acertain condition, and acondenser cooperating with the test. magnet foraccelerating its stopping function.

8. In a switch, rows of sets of bank contacts, brushes for selecting anysaid row, a self-containedv power device for driving a set of brushes ina continuous motion over a plurality of selectable rowsof sets of bankcontacts, a toothed member that moves with said brushes, and a stoppingmember that engages with the toothed member and stops the brushes whenthey reach a desired individual set of bank contacts. a

9. In a switch, rows of sets of bank contacts, a longitudinally movablebrush shaft with brushes adapted to cooperate with the bank contacts, amagnet for setting the brush shaft into a position in its brushes are inline with a said row of sets of bank contacts, a self-contained powerdevice for moving the brush carrier so that its brushes travel in acontinuous motion. over the row onto which they have been set, anarresting member that moves with the brushes when they executecontinuous motion, and a stopping member that engages with the arrestingmembet and arrests it and the brushes when they have reached any desiredset of bank contacts.

10. In a selector switch, rows of sets of bank contacts, brushes forselecting any said row, a self-contained power device for driving saidbrushes to any desired set of contacts in a row andthen to a normalposition, a brush-arresting member that moves with said brush, anelectromagnet whose armature stops the brush on its decnergization, andfield-affecting means for affecting the field of said electromagnet toquicken the brush-stopping action of its armature.

11. An electrically operated conversational switch comprising, rows ofsets of bank con tacts, brushes for selecting any said row, aSelfrontained power device for rotating said brushes over a selected rowof bank contacts, a toothed brush-arresting member that rotates with thebrushes, an electromagnetically operated stopping memberadapted toengage with the teeth of said arresting member to stop the brushes onany individual set of bank contacts, electric circuits local to theswitch for controlling said stopping member, and a line for controllingsaid local circuits.

12. An electrically operated switch comprising, rows of sets of bankcontacts,

brushes forselecting any said row, a spring for rotating the brushesovera selected row of bank contacts, a toothed brush-arresting memberthat rotates with the brushes, an electromagnetically operated stoppingmember adapted to engage with the teeth of said arresting member to stopthe brushes on anyindividualoset of bank contacts, electric circuitslocal to the switch for controlling said stopping member, a line forcontrolling said local circuits, and means for rewinding the springafter each use of the same.

' 13. In a switch, rows of of bank contacts, brushes, a longitudinallymovable brush-carrying shaft, a magnet for moving the shaft step-by-steplongitudinal] y until its brushes are in line with the said row, and aself-contained power device for rotating the shaft continuously untilits brushes reach a desired set of bank contacts.

14. In a selector, sets of bank contacts,

brushes, a power device for driving the brushes over said contacts,means for stopping the brushes on a desired set of contacts, and amagnet for moving the brushes onto the desired set of contacts if thestopping means fails toact. I

' 15. In a selector, sets of bank contacts, brushes, a power device fordriving the brushes over said contacts, a toothed memher that moves withsaid brushes, a stopping pawl that engages withsaid member to stop thebrushes on a desired set of bank contacts, and a magnet with an armaturethat cooperates with the toothed member to move the brushes onto thedesired set of contacts if the stopping pawl fails to act.

16., Aselectorcomprising horizontalcurved rows of bank contact sets,brushes, a longitudinally movable and rotatable brush carrier, astepping mechanism for stepping the brusl'r carrier upwards until itsbrushes reach a desired row of bank contact sets, a power de vice forthen whirling the brush carrier round until its brushcs'reach a desiredbank contact set, and an electromagnetically operated stopping memberwhich engages with the brush carrier to stop the brushes on said bankcontactset.

17. In a power driven hunting switch, bank contacts,brushes that huntfor a desired set of said contacts, a test magnet for controlling themovement of said brushes, and means operative during the hunting actionof said brushes for accelerating the controlling function of the testrelay.

18. A switch comprising, bank contacts, brushes that wipe over the bankcontacts, a brush carrier, a spring for driving thebrushes,

a toothed member attached to the brush car- 1 rier, a stopping pawl thatengages with the toothed member to stop the brushes on a desired set ofbank contacts, an electromagnet for controlling the stopping pawl, acircuit for energizing the clectromagnet to withdraw the stopping )awlfrom the toothed member and to enuhl 1 the ring; to more the brushes,and a second circi i ia'ntaining' the electroin: ashes have i the b1reached a do contact, said second circui aid brushes and some of sci fordriving the brush a brush on niw cit-ow i withd raw 4 m min hruehcz-s,electr' JlilllI contacts, 1 bank contacts.

dev: 1

l 3 ed to the l .7

L ll: 4 7 net to withoraw it ni pawl 'trom i toothed member a1 enablethe :ower

rice to more the brushes, second circuit for niainl mg the electron aguetcnergizeduntil es have reached a at red bank cow iid n:

21 In a power-driven selector. an impulse receiving relay tor receivingelectrical nu- 22. The coni itation ot a switch comprisng bank contacts,ln'ushes, a brush carrier, :1 method wheel adapted to rotate with said 1carrier, at power device 'i'or rotating brush carrier abrush-positiouing pawl Hit coopc ates with said whccl, lines, electricimpulse prod uccrs tor transmitting impulsee over said lines, and anclectroinagnet tor operating said p: wl relatively to said wheel topermitsaid power device to move said lDt'ttlitS stepwise in the rhythmof impulses a-aent mom said impulse producer over said lines.

ilfl. The combin; tion of a switch com n'is- "hank cintacts, brushes abrush carrier, a wheel adapted to rotate with said carrier, :1 powerdevice for rotating 'lllil'ili @arrier, a brush-positioning pawloperates with said wheel, lines, electric racers for t 'ansmittingimpulses d line 1 an electromagnet tor operat- 'd pawl relatively tosaid wheel to pereid power device to move sa id brushes wise in therhythm of impulses sent trom it i inigulse producer over said lines, andan ciectromagnet for lifting said pawl from said wheel.

iZ-l. A rotary switch comprising bank conta cts, brushes, :1 brushcarrie a toothed wheel fixed on the brush carrier, a pawl normallyengaging with the toothed wheel, a power device for driving the brushcarrier, and a sin- Q' Q magnet tor operating said pawl to allow FRITZALDENDORFF.

the iowcr device to more the brushes in steps

